Optical interface assembly and optical module

ABSTRACT

An optical interface assembly, comprising a lens barrel, a lens disposed in the lens barrel, an optical receptacle, a stub disposed in the optical receptacle, and a diaphragm disposed between the lens and the stub. A diameter of a light passing hole of the diaphragm is smaller than a diameter of a light passing surface of the lens. A first end surface of the stub facing the lens is disposed at an inclined angle relative to an axis of the stub. When a light beam is coupled into the stub by the lens, a portion of a return light reflected from the first end surface is reflected to an outside of the light passing hole of the diaphragm.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims priority to Chinese PatentApplication 201910932962.3, filed on Sep. 29, 2019, the entire contentof which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present application relates to the field of passive optical devicetechnology and, more particularly, to an optical interface assembly andan optical module.

BACKGROUND

A connector, an optical fiber end surface, an optical interface, adetector surface, etc., in an optical fiber transmission system may allcause Fresnel reflection, producing reflected lights. A ratio of anoptical power of these reflected lights to a power of an incident lightis called a return loss. A worse return loss indicates stronger lightreflection in an optical fiber link. Impacts of these backward reflectedlights on the system include: 1) weakening an optical signal beingtransmitted; 2) producing a phenomenon of interference with an incidentoptical signal; and 3) lowering a signal-to-noise ratio in a digitaltransmission system. The backward reflected lights may also return to atransmitting light source and have impacts on the light source,including: 1) causing fluctuation of a center wavelength of thetransmitting light source; 2) causing fluctuation of a luminousintensity of the transmitting light source; and 3) damaging the lightsource permanently. Even with an FP (fabry-perot) light source, whosespectral characteristics is not greatly impacted by backward reflection,the reflected lights are amplified by an active region after they enterinto a resonant cavity of the light source, and the reflected lightsjoin a main beam, causing fluctuation of the luminous intensity, whichin turn causes a relative intensity noise (RIN). The RIN is a noise at atransmitting end rather than a receiving end; it will limit the maximumsignal-to-noise ratio that can be possibly obtained in an optical fiberlink and thereby impact reception sensitivity. In addition, the RIN bynature is a broadband noise that reflects the impact generated by theups and downs of the luminous intensity of the light source and thesystem on the electrical noise of the receiving end relative to thepower of the signal.

A symbol error rate of an optical system is higher when a speed of thesystem is higher, a noise bandwidth of a link is broader, a power of anoise is greater, and/or a signal-to-noise ratio is lower. Therefore,for a high-speed optical module, in order to ensure the reliability ofits optical transmission system and the stability of the spectrum andthe power of its transmitting light source, it is necessary to take highreturn loss into consideration when designing points where reflectioneasily occurs to minimize reflection in the link.

In an optical module in which a free-space circulator is integrated,these reflected lights at the module side have a chance to return to thereceiving end. That is, a portion of a signal light at the transmittingend is directly diverted to the receiving end, which results in veryobvious performance deterioration of the high-speed optical device. Theportion of the signal light is equivalent to optical signal crosstalkfrom the transmitting end to the receiving end.

SUMMARY

Purposes of the present disclosure include providing an opticalinterface assembly and an optical module that may effectively improvereturn loss of the optical module and reduce optical crosstalk from thetransmitting end to the receiving end in a high-speed optical module.

In order to achieve one or more aspects of the aforementioned purposes,one embodiment of the present disclosure provides an optical interfaceassembly, including a lens barrel, a lens disposed in the lens barrel,an optical receptacle, a stub disposed in the optical receptacle, and adiaphragm disposed between the lens and the stub. A diameter of a lightpassing hole of the diaphragm is smaller than a diameter of a lightpassing surface of the lens. A first end surface of the stub facing thelens is disposed at an inclined angle relative to an axis of the stub.When a light beam is coupled into the stub by the lens, a portion of areturn light reflected from the first end surface of the stub isreflected to an outside of the light passing hole of the diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section view of an optical interface assembly according to afirst embodiment of the present disclosure;

FIG. 2 is an exploded view of the optical interface assembly of FIG. 1;

FIG. 3 is a side view of FIG. 2;

FIG. 4 is a diagram illustrating an effect of a diaphragm in the opticalinterface assembly according to the first example embodiment;

FIG. 5 is a diagram illustrating an optical interface assembly accordingto a second embodiment of the present disclosure;

FIG. 6 is an exploded view of the optical interface assembly of FIG. 5;and

FIG. 7 is a diagram illustrating an optical module according to a thirdembodiment of the present disclosure.

DETAILED DESCRIPTION

The text below provides a detailed description of the present disclosurein conjunction with specific embodiments illustrated in the attacheddrawings. However, these embodiments do not limit the presentdisclosure. The scope of protection for the present disclosure coverschanges made to the structure, method, or function by persons havingordinary skill in the art on the basis of these embodiments.

In order to facilitate the presentation of the drawings in the presentdisclosure, the sizes of certain structures or portions have beenenlarged relative to other structures or portions. Therefore, thedrawings in the present application are only for the purpose ofillustrating the basic structure of the subject matter of the presentapplication.

Additionally, terms in the text indicating relative spatial position,such as “upper,” “above,” “lower,” “below,” and so forth, are used forexplanatory purposes in describing the relationship between a unit orfeature depicted in a drawing with another unit or feature therein.Terms indicating relative spatial position may refer to positions otherthan those depicted in the drawings when a device is being used oroperated. For example, if a device shown in a drawing is flipped over, aunit which is described as being positioned “below” or “under” anotherunit or feature will be located “above” the other unit or feature.Therefore, the illustrative term “below” may include positions bothabove and below. A device may be oriented in other ways (rotated 90degrees or facing another direction), and descriptive terms that appearin the text and are related to space should be interpreted accordingly.When a component or layer is said to be “above” another member or layeror “connected to” another member or layer, it may be directly above theother member or layer or directly connected to the other member orlayer, or there may be an intermediate component or layer.

First Embodiment 1

FIG. 1 is a sectional view of an optical interface assembly 100according to a first embodiment of the present disclosure. FIG. 2 is anexploded view of the optical interface assembly 100 of FIG. 1. FIG. 3 isa side view of the optical interface assembly 100 in FIG. 2. FIG. 4 is adiagram illustrating an effect of a diaphragm in the optical interfaceassembly 100 according to the first embodiment. As illustrated in FIG. 1through FIG. 4, an optical interface assembly 100 according to the firstembodiment comprises a lens 10 and a stub 20. The lens 10 is disposedinside a lens barrel 40. The stub 20 together with a sleeve 50 and anouter tube 60 form an optical receptacle 70. The outer tube 60 has ametal tube body. The sleeve 50 is disposed inside the outer tube 60, andthe stub 20 is then disposed inside the sleeve 50. A diaphragm 30 isfurther disposed between the lens 10 and the stub 20. A diameter of alight passing hole 31 of the diaphragm 30 is smaller than a diameter ofa light passing surface of the lens 10. As illustrated in FIG. 1, thelight passing hole 31 has a tapered shape or trumpet-like shape having alarger opening and a smaller opening. The aforementioned diameter of thelight passing hole 31 refers to a diameter of the smaller opening of thelight passing hole 31. The aforementioned diameter of the light passingsurface of the lens 10 refers to a diameter of a cross sectional of thelens 10 that is perpendicular to an optical axis of the lens 10. In thefirst embodiment, the diaphragm 30 and the lens barrel 40 are designedto be a single structure. In other embodiments, the diaphragm 30 and thelens barrel 40 may alternatively be separate structures. As illustratedin FIG. 3 and FIG. 4, a first end surface 21 of the stub 20 facing thelens 10 is disposed at an inclined angle relative to the axis of thestub 20 (the axis being a straight line on which an optical axis of thestub 20 is located). A light beam is coupled into the stub 20 by thelens 10. A portion of a return light reflected from the aforementionedfirst end surface 21 is reflected to the outside of the light passinghole of the diaphragm 30 and is blocked by the diaphragm 30 to preventreturn light from entering into an optical device of an optical modulein which the optical interface assembly 100 is disposed. With thediameter of the light passing hole of the diaphragm 30, parameters ofthe lens 10, and other factors taken into consideration, an angle abetween the aforementioned first end surface 21 of the stub 20 and across section of the stub 20 (the cross section being perpendicular toan optical axis of the stub 20) may be selected in the range of 0° to15°. For example, the angle a may be between 10° and 14°, such as 12°,13°, etc. In the first embodiment, a second end surface 22 of the stub20 farther away from the lens 10 is disposed at an inclined anglerelative to the axis of the stub 20 and has a standard angled physicalcontact (APC) end surface. As illustrated in FIG. 3, the direction ofthe inclination of the second end surface 22 is different from thedirection of inclination of the first end surface 21. More particularly,the first end surface 21 is inclined in the x direction while the secondend surface 22 is inclined in the z direction. In other words, thedirection of the inclination of the first end surface 21 is 90° relativeto the direction of the inclination of the second end surface 22. Inother embodiments, the directions of the inclinations of the first endsurface 21 and the second end surface 22 do not have to be 90° from eachother. The directions of the inclinations of the first end surface 21and the second end surface 22 may be at another angle from each other aslong as the first end surface 21 and the second end surface 22 are notparallel.

The light passing hole of the diaphragm 30 added to the opticalinterface assembly 100 has a relatively small diameter, so the diaphragm30 may block stray lights, such as light reflected from an end surface,from returning to the inside of the optical device of the optical modulein which the optical interface assembly 100 is disposed, thuseffectively improving the return loss of the optical interface assembly100. When used in an optical module, the optical interface assembly 100may reduce optical crosstalk from a transmitting end to a receiving endin the optical module, thereby ensuring the reliability of the opticalmodule 100's optical transmission system and the stability of thespectrum and power of the optical module 100's transmitting lightsource.

As described previously, in the first embodiment illustrated in FIG. 1,the light passing hole 31 of the diaphragm 30 has the tapered shape ortrumpet-like shape having the larger opening and the smaller opening.The larger opening of the tapered shape or trumpet-like shape faces thelens 10. The tapered shape or trumpet-like shape may minimize thediameter of the light passing hole 31 of the diaphragm 30 withoutaffecting the passage of the coupled light beam. The inner surface ofthe light passing hole 31 having a tapered shape or trumpet-like shapeis a surface that has undergone blackening treatment. An end surface 32of the diaphragm 30 facing the stub 20 is also a surface that hasundergone blackening treatment. The inner surface and the end surface 32of the diaphragm 30 may absorb stray lights that are reflected or reducethe amount of stray lights that are reflected back into the opticaldevice of the optical module in which the optical interface assembly isdisposed, thus further improving the return loss of the opticalinterface assembly 100. The blackening treatment may be a rougheningtreatment or coating a surface with a light-absorbing coating, etc.

As illustrated in FIG. 3, the aforementioned lens 10 is a plano-convexlens comprising a convex surface 11 farther away from the stub 20 and aflat surface 12 closer to the stub 20. Here, the flat surface 12 isdisposed at an inclined angle relative to a cross section of the lens 10(the cross section being perpendicular to an optical axis of the lens10). An angle b between the flat surface 12 and the cross section of thelens 10 is in the range of 0° to 15°. For example, the angle b isbetween 10° and 12°, such as 11°, 12°, etc. By configuring both thefirst end surface 21 of the stub 20 and the flat surface 12 of the lens10 facing the first end surface 21 to be inclined surfaces at largerangles, reflected light may be reduced effectively.

Second Embodiment

FIG. 5 is a diagram illustrating an optical interface assembly 102according to a second embodiment of the present disclosure. FIG. 6 is anexploded view of the optical interface assembly 102 of FIG. 5. Asillustrated in FIG. 5 and FIG. 6, the second embodiment differs from thefirst embodiment in that the end surface 32 of the diaphragm 30 facingthe stub 20 does not need to undergo blackening treatment. Rather, theend surface 32 is configured to be a tapered surface or a convexspherical surface 32. The tapered surface or convex spherical surface 32is centered and surrounds the light passing hole 31 of the diaphragm 30,and is inclined toward the lens barrel 40. An angle c between thetangent of the tapered surface or convex spherical surface 32 and across section of the diaphragm 30 (the cross section being perpendicularto an optical axis of the light passing hole 31) is greater than orequal to 5° and less than 90°. The greater the angle c is, the better.For example, the angle c may be greater than or equal to 10° and lessthan 90°. A portion of a return light reflected from the first endsurface 21 of the stub 20 is reflected to the tapered surface or convexspherical surface 32 of the diaphragm 30. As the angle c of inclinationbetween the tapered surface or convex spherical surface 32 and the crosssection of the diaphragm 30 is relatively large, the reflected light maybe reflected out of the optical interface assembly 102, therebypreventing the reflected light from entering into an optical device ofan optical module in which the optical interface assembly 102 isdisposed. With a diaphragm having the structure described above, thereis no need to apply blackening treatment to the aforementioned endsurface 32 of the diaphragm, thus simplifying the processing of thediaphragm 30 and lowering the cost.

Third Embodiment

FIG. 7 is a diagram illustrating an optical module 10 according to athird embodiment of the present disclosure. As illustrated in FIG. 7,the optical module 10 according to the third embodiment comprises ahousing 200, a light transmitting end 300 and a light receiving end 400disposed in the housing 200, and an optical interface assembly 700coupled to the aforementioned light transmitting end 300 and lightreceiving end 400. The optical interface assembly 700 may be the opticalinterface assembly 100 or 102 according to any one of the aforementionedembodiments.

The embodiments of the present disclosure provides the followingbenefits. The diaphragm 30 in the optical interface assembly 100 or 102blocks stray lights from returning to the inside of the optical module10, thus effectively improving the return loss of the optical interfaceassembly 100 or 102, reducing optical crosstalk from the transmittingend 300 to the receiving end 400 in the high-speed optical module 10,and ensuring the reliability of the module 10's optical transmissionsystem and the stability of the spectrum and power of the module 10'stransmitting light source.

The series of detailed descriptions above is only intended to providespecific descriptions of feasible embodiments of the present disclosure.They are not to be construed as limiting the scope of protection for thepresent disclosure; all equivalent embodiments or changes that are notdetached from the technology of the present disclosure in essence shouldfall under the scope of protection of the present disclosure.

What is claimed is:
 1. An optical interface assembly, comprising a lensbarrel, a lens disposed in the lens barrel, an optical receptacle, astub disposed in the optical receptacle, and a diaphragm disposedbetween the lens and the stub, wherein the diaphragm includes a lightpassing hole that has a larger opening and a smaller opening; the lenshas a cylindrical shape, the lens barrel includes a cylindrical innerspace in which the lens is disposed, and a diameter of the cylindricalinner space is the same as a diameter of a light passing surface of thelens; the cylindrical inner space of the lens barrel is connected withthe light passing hole of the diaphragm, and the diameter of thecylindrical inner space is the same as a diameter of the larger openingof the light passing hole diaphragm; a diameter of the smaller openingof the light passing hole of the diaphragm is smaller than the diameterof the light passing surface of the lens; a first end surface of thestub facing the lens is disposed at an inclined angle relative to anaxis of the stub; and wherein when a light beam is coupled into the stubby the lens, a portion of a return light reflected from the first endsurface of the stub is reflected to an outside of the light passing holeof the diaphragm.
 2. The optical interface assembly of claim 1, whereinthe light passing hole of the diaphragm has a cone shape or trumpet-likeshape having the larger opening and the smaller opening, the largeropening of the cone shape or trumpet-like shape faces the lens, and adiameter of the cone shape or trumpet-like shape reduces smoothly fromthe larger opening to the smaller opening.
 3. The optical interfaceassembly of claim 2, wherein the inner surface of the light passing holehaving the cone shape or trumpet-like shape is a surface that hasundergone a blackening treatment; and/or an end surface of the diaphragmfacing the stub is a surface that has undergone the blackeningtreatment.
 4. The optical interface assembly of claim 1, wherein an endsurface of the diaphragm facing the stub is a cone surface or convexspherical surface.
 5. The optical interface assembly of claim 4, whereinan angle between a tangent of the cone surface or convex sphericalsurface and a cross section of the diaphragm is greater than or equal to5°, the cross section of the diaphragm being perpendicular to an opticalaxis of the light passing hole of the diaphragm.
 6. The opticalinterface assembly of claim 1, wherein the lens comprises a convexsurface farther away from the stub and a flat surface near the stub, theflat surface and a cross section of the lens being disposed at aninclined angle from each other, and an angle between the flat surfaceand the cross section of the lens is between 0° to 15°; and/or an anglebetween the first end surface of the stub and a cross section of thestub is between 0° to 15°.
 7. The optical interface assembly of claim 6,wherein the angle between the flat surface of the lens and the crosssection of the lens is between 10° to 12°; and/or the angle between thefirst end surface of the stub and the cross section of the stub isbetween 10° to 14°.
 8. The optical interface assembly of claim 1,wherein a second end surface of the stub farther away from the lens isdisposed at an inclined angle relative to the axis of the stub, thedirection of inclination of the second end surface being different fromthe direction of inclination of the first end surface.
 9. The opticalinterface assembly of claim 1, wherein the diaphragm and the lens barrelare a single structure.
 10. An optical module, comprising a housing, anda light transmitting end, and a light receiving end disposed in thehousing, wherein the optical module further comprises the opticalinterface assembly of claim 1.